Many conventional inventions have disclosed different manners of holding a bearing in a bearing cup. For example, a prior art discloses a motor fixing structure for a fan having a metal bearing cup. The fan includes a frame, a circuit board arranged on the frame, a stator assembly mounted on the frame, and a rotor assembly located around an outer side of the stator assembly. The frame is provided at a central area with a support seat, on which a bearing cup is provided. The bearing cup includes a connection sleeve portion and a hollow tube portion. The connection sleeve portion is provided on an outer wall surface with a plurality of receiving sections. The stator assembly is fixedly provided on a bottom with a lower winding frame, which defines a central through hole. A plurality of latching sections is provided on an inner wall surface of the central through hole for correspondingly engaging with the receiving sections on the bearing cup. In this manner, the stator assembly is stably fitted via the lower winding frame to the bearing cup on the support seat without the risk of loosening or separating from the bearing cup due to any external force or being used over a long time, so as to ensure normal operation of the fan.
Furthermore, a prior art discloses a motor fixing structure for a fan having a non-metal bearing cup. The fan includes a frame, a circuit board arranged on the frame, a stator assembly mounted on the frame, and a rotor assembly located around an outer side of the stator assembly. The frame is provided at a central area with a support seat, on which a bearing cup is provided. The bearing cup includes a connection sleeve portion and a hollow tube portion. The connection sleeve portion is provided on an outer wall surface with a plurality of receiving sections, and the hollow tube portion is provided on an outer wall surface with a plurality of ribs. The stator assembly is fixedly provided on a bottom with a lower winding frame, which defines a central through hole. A plurality of latching sections is provided on an inner wall surface of the central through hole for correspondingly engaging with the receiving sections on the bearing cup. In this manner, the stator assembly is stably fitted via the lower winding frame to the bearing cup on the support seat without the risk of loosening or separating from the bearing cup due to any external force or being used over a long time, so as to ensure normal operation of the fan.
Furthermore, a prior art discloses a fan bearing cup structure. The fan includes a frame, a motor unit and a blade unit. The frame is provided at a central area with a support seat, on which a bearing cup is provided, and the bearing cup is provided on an outer wall surface at proper positions with a plurality of latching units. The motor unit has a central opening fitted around an outer side of the bearing cup. The opening is formed on an inner edge thereof with a plurality of recesses, to which the latching units are correspondingly locked. The blade unit includes a fan hub, a rotary shaft, a plurality of blades, and a magnetic member. The rotary shaft is centered in the fan hub and fitted in the bearing cup, and the magnetic member is mounted to an inner wall of the fan hub corresponding to the motor unit. In this manner, the motor unit can be stably held to the bearing cup without the risk of becoming loosened therefrom to sway or displace laterally while rotating or to move upward and separate from the bearing cup.
Furthermore, a prior art discloses a motor, which includes a shaft tube, a stator seat, and a rotor structure. The shaft tube is provided at an upper end with at least one first receiving section. The stator seat has an inner bushing, and an opening defined at a center of the inner bushing. Via the opening, the stator seat is fitted around the shaft tube. At least one second receiving section is provided on a peripheral edge of the opening at the center of the inner bushing of the stator seat corresponding to the first receiving section on the shaft tube and is welded thereto. The rotor structure includes a rotary shaft axially received in the shaft tube.
In the above-mentioned techniques, the bearings are held in place generally by plastic injection molding or metal press fit. In the case of metal press fit, while the metal bearing cup has relatively high heat conductivity and the bearing received therein can have better heat dissipation efficiency to effectively lower the bearing temperature, a higher manufacturing cost is required. On the other hand, in the case of plastic injection molding, while a lower manufacturing cost is possible, the plastic bearing cup could not transfer the heat produced by the bearing during rotation thereof, so that the bearing has relatively higher temperature because the produced heat thereof could not be easily dissipated from the plastic bearing cup.
It is therefore very important to work out a way for forming a fan at reduced manufacturing cost while enabling efficient removal of heat from the bearing.